The alkylation of isoparaffins with olefins using acid acting catalysts, such as hydrogen fluoride, sulfuric acid, and other catalysts of the prior art is of commercial importance in producing relatively high octane motor fuel components. The isoparaffin normally used is isobutane, which is generally reacted with a mixture of butene isomers or a mixture of propylene and butene isomers to provide a reaction product comprising longer chain isoparaffins comprising C.sub.5 - C.sub.9 isoparaffins. The C.sub.5 and heavier products of the reaction are termed alkylate. In a typical alkylation process, the effluent from an alkylation reactor comprising catalyst, unconsumed reactants and alkylate is passed through a separator system, thereby forming a catalyst phase and a hydrocarbon effluent phase. The separated catalyst phase is generally returned directly to the reactor or it may be treated to remove water therefrom if warranted. The hydrocarbon phase thus separated is further processed in a sequence of steps to separate desired alkylate product from other hydrocarbons and particularly those comprising unconsumed reactant materials. Since the reaction between an isoparaffin and an olefin in an alkylation process is effected with a large molar excess of isoparaffin, the hydrocarbon effluent phase contains relatively large amounts of unreacted isoparaffins which must be efficiently and economically recovered for recycle to the alkylation reaction zone. In addition, propane charged to or produced in the alkylation zone must be economically separated in order to minimize undesired build-up of this material as well as that of normal butane. The process combination of the present invention is particularly concerned with improving the operating efficiency and economics of separating the hydrocarbon effluent of an alkylation process to achieve the herein desired results.